Oil well heater



y 7, 1959 E. E. WILLIAMS ET AL 2,893,490

' OIL WELL HEATER 2 Sheets-Sheet 1 t I 14 a; E I i @14- 12 l Filed April4, 1957 i I 0 a 13 11 1 i 4; 14 A .12 I I 5 is 42 41 41 4O 1 40 at I 3INVENTORJ [BA/557E. W/LL/AM: By Baum/w M. M220 y 7, 1959 E. E. WILLIAMSETAL 2,893,490

Y on. WELL HEATER Filed p l 4. 1957 2 Sheets-Sheet 2 v IN V EN TORSEz/vesr E. Mum/ms BY Beeremvo M Khan Wife 6 United States Patent SanFernando, Califi, assignors to Petra-Flow Corporation, Pacoima, Calif.,a corporation of California Application April 4, 1957, Serial No.650,672

Claims. (Cl. 166-60) This invention relates generally to oil wellheaters, and more particularly to electrical oil well heaters.

It is well known that oil wells, particularly those having high paraiiincontent, high viscosity, low temperatures, or other conditions whichtend to limit the flow; either are, or may become, economicallyimpracticable and that upon proper heating of the material they canbecome profitable producers.

There have been a number of heaters designed to attempt to alleviatethis condition. Such heaters employ wide varieties of heating means,such as hot water, ignition of gases within the well, electricalresistance, and the like.

Of all the heaters utilized, the electrical resistance type heaters havemany decided advantages over other types. The advantages include ease ofcontrol, safety of operation, uniformity of temperature, and the otheradvantages inherent in electrical apparatus.

However, the electrical heaters used in the past also have a number ofdeficiencies and disadvantages including, among the more important, thedifficulty of properly inserting the necessary cable to supplyelectrical energy and the serious corrosive effects of the contents ofoil wells upon the insulation and fittings of such cables. Such heatersalso have the inherent disadvantage that certain portions of the heaterbecome hotter than other portions, thus the life of the heating elementsthemselves is affected. In addition, hot spots exist upon which thepetroleum products will coke, which. results in decreased heaterefficiency and further reduction of flow in extreme cases with possibledamage to the producing formations.

Our invention has overcome the disadvantages of other electrical typeheaters by providing enclosed solid conduit covered cable in sectionsthe same length as standard oil well tubingwith special connecting meanssuch that the diiferent lengths may be easily and efiiciently joined anddisconnected, as desired, without damage to the cable and providing acomplete protection for the cable from the corrosive materials withinthe oil well. Our invention further incorporates means for uniformlydistributing the heat within the heater and quickly conducting the sameaway from the heating elements so that they do not become overheated.

Thus it is a major object of our invention to provide electrical cablefor oil well heaters which can be successfully lowered into a well inenclosed conduit and in sections conforming to the standard oil welltubing lengths.

It is a further object of our invention to provide an electrical heaterfor use in oil wells in which the heat is uniformly distributed over theentire surface of the heater.

These and other objects and functions of our invention will be bestunderstood by reference to the detailed description of the invention asset forth in this specification, and the accompanying drawings in which:

Figure 1 is an elevational view of a preferred embodiment of ourinvention;

Figure 2 is a view similar to Figure 1, but with the heater shell andconduit coupling removed, so as to show the internal construction;

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Figure 3 is a section taken at 3-3 in Figure 2;

Figure 4 is a section of the conduit connection and electricalconnection area, taken at 44 in Figure 1;

Figure 5 is a perspective view of. the male and female ends of theelectrical connector;

Figure 6 is a sectionalized view of a length of electrical conduit andcoupling with one length of electrical cable and male and female endsnot sectionalized but shown in position; and

Figure 7 is a perspective view of holding clip for cable.

In the drawings there is seen a portion of oil well tubing 11 which isbent, or offset at 17, and run through a heater shell 10. The heatershell is welded at its upper end to a flange 16 on the tube 11, and thebottom end of the shell is conically tapered at 15, and welded to thetube 11 where it contacts the latter. Conduit 12 passes thru an aperturein the flange 16 and is securely welded thereto. Conduit section 12 isfastened to conduit 12 by coupling 13.

The oil tube 11 is ofi'set as shown at 17 in order to reduce theover-all size of the heater unit. By this means the electrical conduitandoil tube above the heater are all within the extended circumferencearea of the heater shell. By this arrangement the conduit is protectedfrom abrasion and other damage during its descent into a well, whileoperating, and during extraction from the well.

Conduit section 12 is shown to have threads at 14 to accommodatecoupling 13. All succeeding lengths of conduit such as illustrated by12' are threaded at both ends with identical threads-14. Within conduit12 there is a special female electrical coupling unit 50 formed of anyhigh heat resisting and insulating material, such as epoxy resin,capable of withstanding temperatures of the order of 600 F. This specialconnector is used at this position to obviate any possible danger ofover-heating due to proximity to the heater unit.

Inside of the connector 50 are three female contact elements 51, 52, and53. These are connected as shown by crimping or other means of joi'nder55 to Wires 40, 41, and 42. The wires, such as 41,-are shown to becomprised of conductor wire 41a covered'by insulation 41b, whichinsulation-extends partially into the female connector, as shown in thedrawing, in order that there will be a complete insulation seal. Theconnector 50 has a shoulder 54 which rests upon the end of the conduitsection 12 to prevent the cable and connector dropping below the desiredposition and to hold the same in place.

Electrical wires 40, 41, and 42 are connected to ring segments 20, 21,and 22, which are spaced angularly about the circumference of oil tube11 within the heater area. The ring segments '20, 21, and 22 areinsulated from the pipe 11-and have means provided within them (by meansof connecting bar) by which the heater units 23, 24, 25, 26, 27, 28,'29, 30, 31, 32, 33, and 34 are connected in groups of four, or othersuitable numbers to the electrical wires 40, 41, and 42. The ringsegments 20, 21, and 22 are further provided with means (not shown) suchas riveted brackets which are then welded to tube 11 to hold the same infixed connection withtubell.

The heating elements 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, and 34are formed of tubular heater elements, such as tubular metal encased,magnesium oxide insulated, Nichrome wire, such as General Electricproprietary product Calrodj or other electrical heating elements. Theheating elements are connected in pairs at their lower extremities, asindicated, by'flexible connections 35 and 36 joining respectivelypail-s26 and 27, and 25 and 28, and other connectors for each of theother pairs, which connectorsare not shown because of their locationwith respect to the portions visible on .the drawing.

In practice, three-phase electrical current is conducted through thewires '40, 41, and 42, and by the combination series and parallel typeconnection, as indicated, causes uniform heating in all of the heaterelements. The heater elements 23, 24, 25, and 26 are connected at theirupper extremities to conductor 40 through the ring segment '20. Theheater elements 27, 2 8, 29, and 30 are connected through ring segment21 to conductor 41, and the heater elements 31, 32, 33, and 34 areconnected through the ring segment 22 to cable 42. At the lowerextremities the heater elements 23 and 34 are connected together, 33 and24 are connected together, 26 and 27 are connected together, 30 and 31are connected together, and 29 and 32 are connected together.

The entire heater unit thus formed is suspended at its top end by theconnector rings fastened to tube 11 or to the shell 10, or alternatelymay be supported by a separate support ring towhich each heater elementunit is firmly fastened. In this latter instance the connector bars thenare totally insulatedseparate from and do not support a load, the entireload being supported by a con nection between each of the heater unitsclose to the connector rings but separately attached to the tube 11.

If desired, a single, lengthy heating element may be used in place ofeach pair, as indicated.

The electrical heating elements, as shown, are held in position relativeto one another by guide ring 18 which is attached to flow tube 11 nearthe lower extremity of the heating element.

The heat space between shell and flow tube 11 is solidly filled withnon-packing aluminum powder which is selected for this purpose becauseit conducts heat well but does not pack. The heat generated by theelectrical heating elements is conducted by this powder packing anddistributed uniformly to the shell 10 of the heater and the flow tube11. In distributing the heat, hot spots are eliminated and the actualtemperature of the electrical heating elements is maintained at thelowest level cons'istent with the amount of heat required in the heateras a whole.

Electrical cable is connected in lengths, approximately the same lengthas standard oil well tubing, in order to be lowered into a wellconcurrent with the oil well tubing and such that each time a newsection of tubing is connected a new section of cable may be connected.Each length of electrical cable and conduit comprises elements, asindicated in Figure 6, wherein there are shown female connector 50 (eachsuccessive female connector in each conduit section 12 is equivalent toeach other female connector such as connector 50 in conduit section 12at the heater outlet. Therefore, each female connector is labeled andknown as connector 50, whether it is the con nector immediately attachedto the heater elements or any other female connector in another cablesection) with wires 43, 44, and 45, male connector 60 with prongs 61,62, and 63. The entire cable unit is then seen to be enclosed withinconduit 12' with a coupling 13 screwed onto the end in which the femalefitting is located. The female fitting is shown to be located within aconnector unit and it will be seen that because of the shoulder at 54 itcannot retract within the conduit section 12.

The horseshoe-shaped clip 70, shown in Figure 7, is slipped over thefemale connector 50 just below the shoulder 54 and rests upon the end ofthe conduit coupling 13 to hold the cable in position such that the maleconnector at the other end is held well within the conduit and so thatit will not at this time engage the female connector in the cableadjoiner. The cable is thus contained in this position until the conduitis screwed on to the adjoining coupling 13 on'the section of. conduitimmediately beneath the new sectionbeing applied. When the new unit isscrewed up, the clip 70 isremoved from the female connector 50 at whichtime the entire cable unit moves and it then drops downward by force ofgravity, and, also, it may be pushed downward, until the male connectorseats in place within the female connector immediately below it. As thecable is; lowered into position, asindicated, any misalignment of themale connectors 61, 62, and 63 with the sockets 51, 52, and 53 is easilycorrected by slight turning from the upper end. Each of the openings 51,52, and 53 is flared widely at its upper end so that a funneling effectis achieved, and, thus, the male connector prongs are easily guided intoposition. The cable wires are each sufiiciently large and rigid so thatno buckling of the cable will occur during the joining operation.

It will be noted that each of the couplings 13 has a shoulder at 13b atthe end of each set of threads 13:: on each end of the coupling. Thisshoulder causes a joinder of the lengths of conduit at fixed position toachieve uni form length of each section of conduit and coupling, sinceit can be screwed up to this point and no further.

When the length of cable has been seated so that the male connecting end60 is joined with the corresponding female connector 50, the nextsucceeding female connector, located above such male connector will havebecome seated and rest upon the shoulder 54 against the upper end of theconduit 12' and thus will be held in position for receiving the nextsucceeding male connector.

Each section of conduit 12 is preferably strapped or otherwise held tothe corresponding section of oil well tubing 11 in order to hold thesame firmly in position and avoid any possible buckling or flexing whilebeing worked or lowered or removed from a well.

Each of the male and female connectors 50 and 60, other than thoseimmediately adjacent the heater unit, are formed of any reasonablyheat-resistant insulator material.

In practice, our heater is fastened by standard oil well tubingconnecting threads to the bottom section of oil Well tube and loweredinto a well. As each section of oil well tubing is added and the heaterlowered further into the well, an additional length of conduit with thecable mounted within it is added. Upon removal of a portion or all ofthe well tubing, the cable is easily removed section by section in thesame manner. In removal of each cable section, the female connector atthe upper end of each conduit section is gripped and pulled upward untilthe connection at the lower end of the cable has been broken. The clip70 is then inserted in place to hold the cable up in the unit until itis unscrewed. Upon being unscrewed and disconnected, each cable unit isprotected by attaching a cap on the end having the male connector and aplug in the coupling end having the female connector.

While particular reference has been made to this heater being employedat the lower end of an oil well tube, where desired the heater can aswell be located part way up the oil well tube, in which case the end ofthe tube 11 projecting beneath the heater will be threaded to receivelengths below it.

Reference has also been made to standard lengths of oil well tubing andthat the electrical cable section be in these lengths. This, of course,is not essential and the lengths of the cable can be longer or shorterif desired for particular purposes.

While the particular embodiment we have illustrated is fully capable ofperforming the objects and accomplishing the purposes desired, it isrecognized that a number of modifications and changes may be madewithout departing from the scope and spirit of our invention. It is notintended that any limitations be imposed thereby, except such as arerequired by the appended claims.

We claim:

1. An oil well heater of the class described comprising: a length of oilwell tubing; an offset heater shell connected to said tubing by an upperflange to form a sealed, water-tight, annular heating space, said heatershell surrounding said tubing at a spaced radial distance therefrom;finely divided aluminum powder packed within said space; electric heaterelements formed from metal encased, magnesium oxide insulated Nichromewire suspended in said space, said heater elements connected in pairs toone another and formed in a U-shape extending along said tubing, saidelements being firmly attached to said flange independent of said shell;a plurality of sections of threaded rigid metal conduit adapted to beattached to said flange; a metallic threaded sleeve interconnectoradapted to be fastened between said sections of conduit; and lengths ofsemi-rigid copper-sheathed cable encased in a slidable relationshipwithin said sections of conduits; each of said cables consisting ofthree semirigid copper-sheathed conductor wires having a rigid,non-resilient type male connector with three prongs on one end and arigid, non-resilient type female connector with three sockets capable ofreceiving said prongs of said male connector on the other end.

2. An oil well heater of the class described comprising: a length of oilwell tubing; a heater shell connected to said tubing by an upper flangeto form a sealed, watertight, annular heating space; finely dividedaluminum powder packed within said space; electric heater elementswithin said space, said heater elements connected in pairs to oneanother, said elements being firmly attached to said flange; a pluralityof sections threaded conduit adapted to be attached to said flange; asleeve interconnector adapted to be fastened between said sections ofconduit; lengths of electric cable encased in a slidable relationshipwithin said sections of conduits; each of said cables consisting ofconductor wires having a male connector on one end and a femaleconnector on the other end.

3. An oil well heater of the class described: a length of oil welltubing; conduit; a heater shell connected to said tubing by an upperflange to form a sealed, Watertight annular heating space; said heatershell surrounding said tubing at a spaced distance therefrom; finelydivided aluminum powder packed within said space; metal encasedinsulated electric heater elements suspended within said space; saidheater elements connected in pairs to one another and formed in aU-shape extending along said tubing; said elements being firmly attachedto said flange independently of said shell; a plurality 'of sections ofthreaded rigid metal conduit adapted to be attached to said flange; ametallic sleeve interconnector adapted to be fastened between saidsections of conduit; lengths of semi-rigid electric cable, encased in aslidable relationship within said sections of conduit, each of saidcables consisting of semi-rigid conductor wires having a nonresilienttype male connector with prongs on one end and a non-resilient typefemale connector with sockets on other end.

4. In an electric oil well heating system, means for the conduction ofthree phase electric current to an electric heater consisting of:sections of rigid metallic hollow conduit of a predetermined lengthcorresponding to lengths of normal oil well tubing, said conduit havingthreaded ends on the outer periphery; each of said sections of conduithaving a hollow threaded metallic connector engaged on one end thereof,each of said connectors having perpendicular shoulders therein such thateach connector may be screwed only to a predetermined length upon saidsections of conduit; each of said sections of conduit having locatedtherein in a slidable relationship three lengths of semi-rigid,copper-sheated wire of equal corresponding predetermined length parallelto each other and to said conduit, an insulated solid male connectormolded one one set end of each set of said wire; said male connectorhaving a plurality of nonmetallic, non-corrosive prongs protruding fromsaid insulated connector and joined therein to said semi-rigid wires; aninsulated non-resilient female connector at the other end of each set ofsaid semi-rigid copper-sheathed wires having a plurality of socketsadapted to receive the prongs of said male connector which are thereinjoined to said wires, said sockets having a flanged aperture andmetallic means for conduction of current along the circumference of eachsocket, a downwardly facing shoulder on said female connector suitableto engage the end of a section of conduit about said cable causing saidfemale connector to possess two diiferent exterior diameters.

5. In an electric oil well heating system means for conduction ofelectric current to an oil well heater consisting of: sections ofconduit of a predetermined length corresponding to lengths of normal oilwell tubing, said conduit having threaded ends on the outer periphery;each of said sections of conduit having a connector located on one endthereof, each of said connectors having a perpendicular shouldertherein, such that each connector may be screwed only to a predeterminedlength upon said sections of conduit; each of said sections of conduithaving located therein in slidable relationship lengths of semi-rigidwire of equal corresponding predetermined length parallel to each otherand to said conduit; a male connector molded on one end of each set ofsaid wire; said male connector having prongs protruding from saidconnector and joined therein to said wires; a female connector at theother end of each set of said wires having sockets adapted to receivethe prongs of said male connector which are therein joined to saidwires, said sockets having means for conduction of current along thecircumference of each socket; and a downwardly facing shoulder on saidfemale connector suitable to engage the end of a section of conduitabout said cable.

References Cited in the file of this patent UNITED STATES PATENTS1,169,262 Hufi Jan. 25, 1916 1,504,208 Brine Aug. 12, 1924 2,306,206Dalsleish Dec. 22, 1942 2,742,555 Murray Apr. 17, 1956

